In this talk, I shall focus on a particular phenomenon that could play a role in the process of thermalization, namely the strong amplification of very soft gluon modes, possibly leading to the formation of a transient Bose-Einstein condensate. Aside from its potential relevance to the thermalization problem, the formation of such a condensate in relativistic systems is an interesting problem in itself. The onset of condensation in such systems has been studied recently using kinetic theory in the approximation of small scattering angles. Numerical evidences for the scaling regime that develops near the onset of condensation will be presented.