erupt, spout, emit, flush out
噴 centers on forcefully sending something out from an opening: erupting, spouting, emitting, or flushing out material.
噴 combines 口 (mouth) with 賁, which likely contributes the sound and carries a sense of bursting forth or gushing. The overall structure suggests something forcefully expelled from an opening.
The mouth 口 on the left and the bursting 賁 on the right together show a mouth violently spouting something out, like a volcano erupting.
For フン, imagine a volcano erupting with a loud fun sound: fun -> フン, as lava and ash spout out.
eruption; volcanic eruption
jet; spray; emission; spouting
spewing; gushing; spouting; eruption; effusion
water fountain
to emit; to spout; to spurt; to boil over
atomizing; spraying
(eruption of) smoke
gas (fumes)
material ejected during a volcanic eruption (cinders, scoria, etc.)
jet (of water)
bursting out laughing
(volcanic) crater
Strombolian eruption
Hawaiian eruption
Vulcanian eruption
fissure eruption
extrusive rock; effusive rock
projectile vomiting
injection nozzle; spray nozzle
injection nozzle; jet nozzle