noun
burn blister
Specifically a blister caused by a burn, not a friction blister.
やけどをしたところに火ぶくれができた。
A burn blister formed where I got burned.
火ぶくれはつぶさないほうがいい。
It's better not to pop a burn blister.
水ぶくれ is a general blister (often from friction), while 火ぶくれ is specifically from a burn.
Compound of 火 (hi, 'fire') and 膨れ (fukure, 'swelling'), with rendaku voicing to ぶくれ.