Explain why placing a dented table tennis ball in a pot of boiling water will remove the dent?

The main reason why a dented table tennis ball when placed in a pot of boiling water will get its dent removed is because the air inside the table tennis ball will expand and push out the dent in the ball. The hot water within the pot will slowly expand the air within the dented ball and the air will try to occupy more space. So to create greater space, the air will push the dent in the ball outwards making the ball normal.