This paper is concerned with bubble contraction in porous media otherwise filled with viscous fluid. We suppose that an external pressure is applied to the (fixed) boundary of a porous medium, forcing a bubble to contract towards a point. By using the Baiocchi transform, we are able to give a rather complete asymptotic description of the process at times just before the bubble vanishes. The application of time-reversal to the results leads to implications for bubble nucleation.