There's little doubt that the 20th century was full of technological breakthroughs and scientific discoveries that changed history.

But the 21st century could go one step further, and investors need to be ready to see the opportunities in technologies that create a new market or disrupt an existing one.

In the last decade, we've seen iTunes turn the music industry on its head. The emergence of smartphones such as the BlackBerry and the iPhone, along with the social media revolution, has transformed the way we communicate.

What will be next? Research analysts at Citigroup have been investigating the innovations that could challenge the status quo.

3-D printing, creating three-dimensional solid objects from digital models, is gathering momentum. Printers that once cost $30,000 now are priced at about $3,000 and have the potential to rewrite the rules of global manufacturing.

"This is a huge technology, it's definitely going to be very big," James Ross, senior portfolio manager at Alliance Bernstein, told CNBC. "It will disrupt traditional manufacturing big time. You don't need nearly as many factories in China—or Africa, if that's next."

The market for 3-D printing was estimated at about $1.7 billion in 2011 and could hit $6.5 billion by 2019, according to research firm Wohlers Associates.

No smoke without fire? The growth in tobacco-free, battery-powered products is making even Big Tobacco sit up and take notice. The electronic-cigarette industry is moving quickly. Sales were $400 million to $500 million in 2012 and will "at least" double this year, Wells Fargo's Bonnie Herzog told CNBC.

"We're actually predicting that consumption of e-cigs could surpass consumption of traditional cigarettes in the next decade," she said.

Mobile payments can include storage in digital wallets or a payment initiated or accepted from a mobile device such as a phone or tablet. Canada-based IE Market Research forecasts $1 trillion of transaction value by 2016.

In the mobile sector, near-field communication (NFC) is slowly emerging as the market choice for device makers. Developed over the last five years, NFC lets consumers tap and pay for items using their smartphone.

"We've been promising NFC for the last five years, and it was always going to be next year," Bill Gajda, global head of Visa Mobile, told CNBC. "I'm more confident now than ever that we're going to see this thing take off during 2015."

Hydraulic fracturing, or "fracking," has led a revolution in gas and oil production in the United States. The technology is unlocking oil and shale gas resources, spurring economic activity and giving industry a competitive edge with less expensive gas and electricity prices.

Fracking, horizontal drilling and subsea exploration will expand the global supply of fossil fuels, according to Citi.

"Subsea processing equipment has the potential to be a $100 billion per annum market by the next decade," Citi analysts said.

Because of oil sanctions, Iran has become the world leader in vehicles fueled with natural gas. The technology could be poised to go global as countries move to improve fuel economy and reduce emissions, and strive for energy independence.

The number of natural gas vehicles jumped from less than fifty thousand in 2005 to almost 2.9 million in 2011, according to Citi.

Take Waste Management, the largest waste collection and disposal company in the U.S., already uses compressed natural gas to fuel roughly 1,400 garbage trucks. In the next five years, about 80 percent of new trucks will be powered by natural gas.

The pay-TV industry is one of the largest and most lucrative segments of the entire U.S. media ecosystem, but trouble is on the horizon.

Hardware developers such as Roku have had success selling new set top boxes, with content streamers including Netflix, Hulu, Amazon Prime and YouTube moving into the sector. They offer a cheaper, Web-based video service, bypassing conventional pay-TV suppliers.

In its latest earnings report, Netflix said 2 million U.S. customers and 1 million international customers had been added to its streaming service, for a total of more than 36 million streaming users. Meanwhile, research firm Nielsen reported that traditional TV ratings have been falling in the past 12 to 18 months.

Cloud computing is making waves, with service providers falling over themselves to offer the biggest and best solution.

Software-as-a-Service (SaaS), a form of cloud computing, is an Internet-based software delivery model, where customers use their browser to access software running from public data centers. Examples include Google Apps, Microsoft 365 and Amazon Web Services.

The cloud software market had revenue of $22.9 billion in 2011, up 30.9 percent from 2010, according to the latest research from IDC. The market intelligence firm expects cloud software to grow to $67.3 billion by 2016—a compound annual growth rate of 24 percent—and projects that SaaS delivery will significantly outpace traditional software product delivery, growing nearly five times faster.

Citi said that software-defined networking (SDN), which uses software instead of hardware to simplify computer networks, could be an "important and necessary game-changer in network architecture."

The worldwide SDN market for the enterprise and cloud service provider segments is forecast to grow from $360 million this year to a $3.7 billion by 2016, according to IDC.

Notable users include Google, Facebook, Verizon and Deutsche Telekom, according to Citi, which projects that over the next three to five years, SDN deployment will see rapid growth off a small base.

Startups such as Big Switch, Plumgrid, Embrane and Vyatta are set to share this burst of revenue, Citi said, with larger network vendors including Cisco, Juniper, Alcatel Lucent, IBM, HP and Dell also set to gain.

Already competitive in many domestic markets worldwide, solar photovoltaics could take market share from future energy demand as well as snatching away a share of previously installed solar technology.

"The difference between where we were 10 to 20 years ago with solar and where we are now is a huge change in the cost of the power produced. ... The actual costing of the solar [photovoltaic] panels is coming into line with the rest of the world," Simon Weeden, Citi's head of European telecom research, told CNBC.

"Here's an example of a cost that's really coming down into line with the alternatives because of mass production and because of the inventiveness of the people that are putting it together," he added.

Solar will receive $1.3 trillion of investment in new capacity between 2012 and 2035, representing 13 percent of total global investment in power generation—ahead of gas and only marginally behind coal, according to the International Energy Agency.

Genomics—the study of human genes and their functions—is beginning to have an impact, according to Citi, adding that personalized medicine, a model that proposes customizing health care for the patient, has mass potential.

"Even though the understanding of genomic data and the relationship it has to health care status remain in an early stage, current applications in cancer genetics, non-invasive pre-natal testing, and companion diagnostics are already demonstrating the potential of sequencing technology," Citi analyst Amit Bhalla said in a research note.

Cost is also a factor. The price for sequencing a human genome was $100 million in 2001 but is now $10,000, according to Citi.