Well Miss Butz can perform a magic trick too. Well, let's watch. Explain the real reason to them. The egg is too large to fit into the bottle by itself, so we need to give it a little help. When we sit the egg on top of the bottle, it is balanced there because the air pressure pushing down on the egg, the air pressure pushing on the sides of the egg, and the air pressure pushing from the bottom of the egg, or the inside of the bottle are all the same, equal, in balance.
Warm temperatures make air expand or get larger.
When this happens, the air grows too big to fit into the bottle, so it wants to escape or get out. But since there is an egg blocking the exit of the bottle, the air must push its way passed the egg, this is why the egg bounces a little. That is how the egg gets sucked into the bottle. Now you can pretend to be like Harry Potter and do your own magic mystery tricks.