Classically, a supercritical fluid (SF) is treated as a single-phase fluid without bubbles, droplets and related interfacial effect, thus it is difficult to generate coloration. Here, we assume the pseudo-boiling-induced coloration in supercritical fluids. A smart experimental setup is established, consisting of a well-controlled pressure and temperature chamber integrated with a suspended pulse-voltage-driven microheater, thus a localized pseudo-boiling region can be achieved. Blue light is demonstrated on a millisecond timescale, and the Rayleigh scattering mechanism is concluded. Two independent theories, i.e., the multiphase-percolation theory and the molecular dynamics, are developed for quantitative analysis, both of which show the existence of self-sustained nanoscale voids and/or clusters acting as effective scatterers, where the light scattering intensities in the pseudo-boiling region are 4-5 orders of magnitude larger than the bulk fluid region. Our theoretical work extends the coloration to general fluids. The multidisciplinary crossover investigation helps to understand the complicated supercritical interface phenomena.