By quenching the strength of interactions in a partially condensed Bose gas
we create a "super-saturated" vapor which has more thermal atoms than it can
contain in equilibrium. Subsequently, the number of condensed atoms (N0​)
grows even though the temperature (T) rises and the total atom number decays.
We show that the non-equilibrium evolution of the system is isoenergetic and
for small initial N0​ observe a clear separation between T and N0​
dynamics, thus explicitly demonstrating the theoretically expected "two-step"
picture of condensate growth. For increasing initial N0​ values we observe a
crossover to classical relaxation dynamics. The size of the observed
quench-induced effects can be explained using a simple equation of state for an
interacting harmonically-trapped atomic gas.Comment: 4 pages, 4 figure