It's a metaphor. Back before coffee makers like we have today people use to percolate coffee which was a pot or machine that heated water and the water rose to the top through a tube and the ground coffee was up top and hot water would pass through the ground coffee reheat and then back up and so on. It became a metaphor when you could tell someone was angry as they would say you could see his anger percolate.

Liquid "percolates" when it oozes through a porous substance like dirt. The commonest use of the word is "percolator," a kind of coffeemaker in which boiling water bubbles up through a funnel and tube and percolates through the coffee. A percolator makes a distinctive noise as the water begins to boil... blup, blup, BLUP, BLUP BLUP." So it is a kind of boiling noise, and "boiling" is a common metaphor for getting angry. These are all ways of saying the same thing: "He could hear the anger percolate again." "He could hear that the other person was coming to a boil again." "He could hear that the other person was getting steamed up again." "He could hear that the other person was about to blow his top."