Heating up food using microwaves does exactly that. It works because the waves are emitted within a certain frequency range that affects the water content within it, from which the heat spreads to the rest of the food over time.

Hey you know, sometimes you don't have a kettle on hand and even if you do, it's all crusty and gross looking. Plus, it takes forever to boil the water. Microwaves on the other hand: you just put the water in it, wait a little bit, bada bing badda boom, it's done and ready to go. So like, if microwaving water is a crime, then lock me up