Learn French: Au bout de dix minutes, la sonnerie m'a tellement énervé que j'ai raccroché. - At the end of ten minutes, the ringtone annoyed me so much that I hung up.

Au bout de specifically emphasizes the expiration of a duration, literally meaning 'at the end of'. While après dix minutes is grammatically correct and means 'after ten minutes', au bout de dix minutes highlights that a limit or breaking point was reached, which fits perfectly with the speaker losing their patience.

How does the tellement ... que structure work in this sentence?

It translates to 'so much ... that'. When modifying a verb in compound tenses like the passé composé, the adverb tellement is typically placed between the auxiliary verb (a) and the past participle (énervé). The que then introduces the consequence of that annoyance: j'ai raccroché.

La sonnerie is feminine, so why doesn't énervé have an extra 'e' at the end?

In the passé composé with avoir, the past participle agrees with the preceding direct object, not the subject. The subject is la sonnerie, but the direct object is m' (me). Because énervé doesn't have an extra 'e', we know the speaker of this sentence is male. If a woman were speaking, it would be written as m'a tellement énervée.

Is énervé related to feeling nervous?