Infrared, Raman, and nonlinear spectroscopies are powerful probes of liquid structure and dynamics. We use vibrationally adiabatic mixed quantum-classical molecular dynamics approaches to calculate vibrational spectra for dilute solutes as a means to explore the underlying condensed-phase dynamics. This approach has the advantage of accounting for solute-solvent interactions more accurately than standard approaches employing perturbation theory. Fluctuations in the vibrational energy levels have been calculated "on the fly" for I₂ and ICl solutes in liquid Xe. We find a particular solute-solvent interaction dominates the vibrational lineshift at any given instant in time, which is reminiscent of the independent binary collision model from gas-phase dynamics. However, multiple interactions are required for a quantitative model of the frequency distribution. Mechanistic insights gained from these simulations will be presented with the aim of developing a general approach toward interpretation and prediction of spectra.