  The non-local in space two-phase Stefan problem (a prototype in phase change
problems) can be formulated via a singular nonlinear parabolic
integro-differential equation which admits a unique weak solution. This
formulation makes Stefan problem to be part of the General Filtration Problems;
a class which includes the Porous Medium Equation. In this work, we prove that
the weak solutions to both Stefan and Porous Media problems are continuous.
