Blow a balloon and keep it over the flame of a candle. It immediately pops and the candle goes off.
Fill another balloon with water (partially or fully). And lower it, until the balloon touches the flame.
The balloon doesn’t pop this time.
How it works-
The first time, the balloon pops because rubber acts as an insulator. The force of the air from the popped balloon also blows the candle off. However, when the balloon is filled with water, it doesn’t pop. This is because water inside the balloon conducts the heat and keeps the surface (rubber) safe, preventing it from bursting.