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."