(Of a heated liquid) having just stopped boiling.
(colloquial) no longer continuing or active.
the deal has come off the boil
(colloquial) No longer going smoothly or working well.
(sports, colloquial) No longer playing exceptionally well.
Source: en.wiktionary.orgI've not been an admirer of contemporary music since punk rock went off the boil in 1977, but once a year I'll listen to 'Spiral Scratch' by the Buzzcocks, or 'Hippy Hippy Shake' by the Swinging Blue Jeans. Otherwise, I can put up with Chopin or shakuhachi flute in the background. Billy Childish