become vs pop up

become

verb
  • begin to be; turn into. 

  • To be proper for; to beseem. 

  • Of an adornment, piece of clothing etc.: to look attractive on (someone). 

  • To come about; happen; come into being; arise. 

pop up

verb
  • To appear without warning. 

  • To display as an alert, advertisement, etc. that suddenly appears on screen. 

  • To come up with a "pop" sound. 

  • (Of an alert, advertisement, etc.) To suddenly appear onscreen. 

How often have the words become and pop up occurred in a corpus of books? (source: Google Ngram Viewer )