Old English berstan (intransitive) "break suddenly, shatter under pressure" (class III strong verb; past tense bærst, past participle borsten), from a West Germanic metathesis of Proto-Germanic *brestanan (cf. Old Saxon brestan, Old Frisian bersta, Middle Dutch berstan, Low German barsten, Dutch barsten, Old High German brestan, German bersten "to burst"), from PIE root *bhreus- "to burst, break, crack" (see bruise (v.)).
The forms reverted to brest- in Middle English from influence of Old Norse brestan/brast/brosten, from the same Germanic root, but it was re-metathesized late 16c. and emerged in the modern form, though brast was common as past tense through 17c. and survives in dialect.
Of extended or distended surfaces from 1530s. Figuratively, in reference to being over-full of excitement, anticipation, etc., from 1630s. Transitive sense ("to cause to break") is from late 13c. Meaning "to issue suddenly and abundantly" is from c.1300 (literal), mid-13c. (figurative). Meaning "break into sudden activity or expression" is from 1680s. Related: Bursting.