  Possible hadronization of supercooled QGP, created in heavy ion collisions at
RHIC and SPS, is discussed within a Bjorken hydrodynamic model. Such a
hadronization is expected to be a very fast shock-like process, what, if
hadronization coincides or shortly followed by freeze out, could explain a part
of the HBT puzzle, i.e. the flash-like particle emission
($R_{out}/R_{side}\approx 1$). HBT data also show that the expansion time
before freeze out is very short ($\sim 6-10 fm/c$). In this work we discuss
question of supercooled QGP and the timescale of the reaction.
