intumesce (verb) – to swell or enlarge abnormally; to bubble up
BREAKDOWN: IN- (in) + TUM- (swell) + -ESCE (action or process)
— intumescence is the process of swelling up or the state of being swollen; a swollen mass (also tumefaction)
This word is built on the root TUM-, which means to swell or to be proud.
Common TUM- words include tomb and tumor.
More esoteric TUM- words include contumely, tumefacient, and tumulous.