buku-buku
The sound of bubbles forming and rising in liquid — blowing bubbles in a drink, water boiling, or someone sinking underwater.
💡A child blowing bubbles in milk — 'The milk went buku-buku with bubbles.'
水がぶくぶくと泡立っている。
The water is bubbling buku-buku.
The pot of water started to ___ as it reached boiling point.
鍋の水が沸騰し始めて○○と泡が出てきた。