A lattice Boltzmann model for the propagation and sharpening of phase boundaries that arise in applications such as multiphase flow is presented. The sharpening is accomplished through an artificial compression term that acts in the vicinity of the interface and in the direction of its surface normal. This term is embedded into the moments of the two-relaxation-time discrete velocity Boltzmann partial differential equation, which is discretized in space and time to yield a second order algorithm. Stringent one- and two-dimensional tests for sharp propagating fronts are performed. The proposed model is shown to conserve the phase field to machine precision and allows narrow interfaces to advect correctly with the flow field with minimal lattice pinning and facetting.