When you, a baby, or any other entity that can get 'inside' a cauldron is inside a cauldron and is pushed via piston, said entity will glitch through the bottom of the cauldron. Note that if this happens, you will be stuck inside the cauldron until you break it. Also, if you don't have the wall, you will glitch through the cauldron but also be pushed forwards, so that you end up having the cauldron face you at eye level.

How to reproduce:

1) Build device as shown in snapshot
2) Step inside cauldron
3) Activate piston with lever