  Recent experiments suggest that shear-enhanced growth of concentration
fluctuations in polymer solutions is strongly influenced by solid boundaries.
We analyze the dynamics of a model of a sheared polymer solution, accounting
for the effect of stress variations on mass flux and for wall-slip. If (and
only if) these effects are present, the flow exhibits a boundary-localized
instability consistent with experimental observations. Even in the absence of
flow instability, thermally-driven concentration fluctuations are significantly
enhanced near the boundary.
