沸騰【ふっとう】
boiling, seething, becoming heated (e.g. of a debate), excitement, agitation, fermentation, soaring (of prices), shooting up
沸かす【わかす】
to boil, to heat, to excite, to melt (metal)
湯沸かし器【ゆわかしき】
water-heater, water-boiler
沸き起こる【わきおこる】
to well up, to burst, to arise
沸き返る【わきかえる】
to boil up, to seethe, to get excited, to be in an uproar