You should watch this activity in the company of a parent or teacher.

Light a candle and watch what happens to the solid wax as the wick burns.

The wax melts and turns into a pool of liquid wax. Then the wax dribbles away and, when it is away from the flame, it cools. Then it turns back into solid wax again.

If you put a flame to the dripped wax it would melt.

This is a reversible change.