Cauldron bouncing bug

What I expected to happen was...:
I was trying to make a guillotine and i expected a player head to fall into it!

What actually happened was...:
When you throw it into the couldron it bounces!

Steps to Reproduce:
1. Place a cauldron
2. Get an item in your inventory
3. Throw it in the cauldron
4. The item bounces