seethe, boil, ferment, uproar, breed
沸 centers on liquid becoming agitated by heat: boiling or seething. The extended senses of fermenting, uproar, and breeding all share the idea of something bubbling up or becoming turbulent.
沸 combines 氵 (water) with 弗, which likely contributes the sound and the idea of something being forcefully expelled or rising, as in boiling water.
Water 氵 beside 弗, which looks like a bow with arrows, suggests water shooting up like arrows when it boils.
For フツ, imagine a pot of water boiling so fiercely it makes a 'futs futs' sound: futs -> フツ.
to grow hot (e.g. water); to boil
boiling; seething
to boil; to heat (a liquid); to prepare (a bath, hot drink)
boiling point
boiling up
water heater; water boiler
simmer; bubble out; flow out
to boil strongly
teakettle; kettle
to well up; to burst; to arise
what a joke!; don't make me laugh!
what a joke!; don't make me laugh!
coffee pot; coffee maker; percolator
molar elevation
(enjoying) tumultuous popularity
ebullism; formation of gas bubbles in bodily fluids
azeotrope
chabazite; chabasite
analcite
stilbite; desmine