We formulate the theory of surface tension driven Stokes flow set up b
y an active scalar with zero diffusivity. The 3D hydrodynamic problem
can be reduced to a 2D nonlinear evolution equation involving only fre
e surface quantities. For a semi-infinite layer it can be rigorously d
emonstrated that the solutions to this equation blow up in finite time
and develop singular forms. The new type of nonlinearity plays a univ
ersal role in the description of interfacial turbulence.