  We solve the relativistic Navier-Stokes equations with homogeneous
boost-invariant boundary conditions, and perform a stability analysis of the
solution. We show that, if the bulk viscosity has a peak around $T_c$ as
inferred from QCD-based arguments, the background solution "freezes" at $T_c$
to a nearly constant temperature state. This state is however highly unstable
with respect to certain inhomogeneous modes. Calculations show that these modes
have enough time to blow up and tear the system into droplets. We conjecture
that this is how freeze-out occurs in the QGP created in heavy ion collisions,
and perhaps similar transitions in the early universe.
