A couple of days ago I mentioned the idea of supercooled water existing in liquid form well below the freezing point. Perhaps more dangerous is another delayed phase transition: water can exist in liquid form at temperatures much higher than the boiling point and can flash boil when subject to a disturbance. This usually happens in the microwave oven, which is why sometimes people recommend placing a wooden skewer into a cup of water that you are heating for tea.

Check out the videos here for some examples. Do not try this at home: you can be badly burned by experiments like this. IIf you don’t particularly value your life, you could refer to Bill Beatty’s list of unwise microwave experiments for more dangerous ways to learn about science.