acerbate vs boil over

acerbate

verb
  • To exasperate; to irritate. 

  • To make bitter or sour. 

adj
  • Embittered; having a sour disposition or nature. 

boil over

verb
  • To reach the point where aggressive action is taken. 

  • To boil to such an extent as to overflow its container. 

How often have the words acerbate and boil over occurred in a corpus of books? (source: Google Ngram Viewer )