If you're tired of waiting and you want your kettle to boil faster, there are only two things you can do. One is to use more electric current—in other words, buy a more powerful kettle; the other use is to use less water.
"Instant" water boilers/dispensers (such as the Breville Hot Cup and the Morphy Richards Meno), which can boil as little as a cupful of water really quickly, combine these methods. They use a more powerful heating element than an ordinary kettle (typically 3000 watts or more) and they're designed so the element can operate safely in contact with only a small amount of water. If you're boiling only (say) a quarter of a liter of water, you need only a quarter as much energy—say 100,000 joules. And if you're supplying that energy with a 3000 watt element, do the math and you'll find you can do it in about 30 seconds instead of 2.5 minutes. Can you see another great benefit here? If you're boiling an entire kettle to make just a single hot drink, you're effectively wasting three quarters of the energy you're consuming. Boiling only as much water as you need saves you a significant amount of money—and helps the environment too.