While doing some heating processes, we use to put some porcelain pits in it. What is the role of it?

Question

For some preparations say some double stage preparations, What purpose we are adding this.

Here my answer is,by doing so some minute porous parts in the porcelain pit(thats why it is called as 'por'celain pit)which absorbs the airy bubbles producing while bumping. Which controls creation of airy particles, and avoid bumping.

Answer 1

These are there to stop bumping, that is uncontrolled boiling.
Sometimes pieces of porous pot are added as a catalyst, to give a large surface area to the reactants.