  Liquids in systems with spherically symmetric interactions are not
thermodynamically stable when the range of the attraction is reduced
sufficiently. However, these metastable liquids have lifetimes long enough that
they are readily observable prior to crystallisation. Here we investigate the
fate of liquids when the interaction range is reduced dramatically. Under these
conditions, we propose that the liquid becomes kinetically unstable, i.e. its
properties are non-stationary on the timescale of structural relaxation. Using
molecular dynamics simulations, we find that in the square well model with
range 6% of the diameter, the liquid crystallises within the timescale of
structural relaxation for state points except those so close to criticality
that the lengthscale of density fluctuations couples to the length of the
simulation box size for typical system sizes. Even very close to criticality,
the liquid exhibits significant structural change on the timescale of
relaxation.
