[en] We identify the major physics milestones in the development of strange hadrons as an observable for both the formation of a quark-gluon plasma (QGP), and of the ensuing explosive disintegration of a deconfined matter fireball formed in relativistic heavy-ion collisions at 160-20 A GeV. We describe the physical properties of the QGP phase and show agreement with the expectations based on an analysis of hadron abundances. We then also demonstrate that the m_{perpendicular} shape of hadron spectra is in qualitative agreement with the sudden breakup of a supercooled QGP fireball. (author)