Cut a candle short, so that when you attach it to the bottom of a bowl, it doesn't reach the bowl's rim.
Fill the bowl with water almost up to the candlewick, and light the candle.
Now all you need is some patience. The candle will burn, and you would expect the flame to finally touch the water and extinguish. Wouldn't you?
... Here's the trick: the water absorbs some of the candle's heat. Thus, the candle's outer layer does not get as hot as the inner part, and doesn't melt. This forms a protective "wall" surrounding a small pit, in which the candle continues to burn.
Did you guess this beforehand?... :-)