Since almost 60 years, space-based gamma-ray observatories routinely detect random, brief gamma-ray bursts from deep space. These bursts signpost rare, cataclysmic events that take place in distant galaxies. During the last two years, the two brightest gamma-ray bursts so far, GRB221009A and GRB230307A, have been detected and could be studied in detail. Both of them are special in ways that go well beyond their stunning brightness: their observation provides a route to investigating the peculiar physical conditions necessary for the synthesis of the heaviest elements - such as Uranium - and the formation and annihilation of antimatter.