  On the basis of the NJL model as an effective theory of QCD and analogies
with condensed matter physics, we extract simple physical pictures of the
chiral phase transition at finite temperature $T$ and/or chemical potential
$\mu$ and predict interesting phenomena associated with the phase transition
which may be seen in relativistic heavy-ion collisions to be performed in RHIC
or LHC. We indicate that the macroscopic equation describing non-equilibrium
phenomena of the chiral transition like DCC might be given by a diffusion-like
equation rather than a wave equation especially when the baryon density is
present.
