What should you never microwave? what is the science behind it?

WATER. Don’t freaking try to heat up water in the microwave for tea/coffee or whatever reason.

When you heat water on a pan over a stove top it starts to bubble. Bubbles release the energy which the water stores during heating up. Thus the water maintains the boiling temperature.

When you heat the same water in a microwave, it does not boil. So it does not release the energy. The water quickly can cross the boiling temperature to a state called superheated water. When you take out the mug of water from the microwave if you see the surface is too still, maybe the water is superheated.

If you drop something in that water before it releases some energy, you can get a little blast of hot water which can easily burn you.