The phenomenon is called superheating and it can be acheived in a microwave with enough power, most kitchen microwaves have enough power to achieve superheating. What happens is that the water explodes without any outside disturbance. Watch till the end to see how exactly the water reacts to superheating.
This Experiment is very dangerous – DO NOT ATTEMPT TO DUPLICATE THE VIDEOS AT YOUR HOME!
What happens if You Remove From the Microwave Just Before the Explosion
If in case you have superheated the water but removed it from the microwave just before exploding, do not touch the water as any disturbance will make the water molecules explode, watch the above video to see exactly how water superheated past its boiling point and removed from the microwave will react.