A system for measuring real-time tissue reflection spectral characteristics during ablation includes a catheter for collecting light reflected from tissue undergoing ablation, a detection component for separating constituent wavelengths of the collected light, a quantification apparatus for generating measured light intensity data of the collected light, and a processor for analyzing the data in relation to time. A method for monitoring formation of steam pop during ablation includes delivering light to tissue, delivering ablative energy to the tissue, measuring the reflectance spectral intensity of the tissue, and observing whether the measured reflectance spectral instensity (MRSI) initially increases in a specified time period followed by a decrease at a specified rate. If the MRSI does not decrease, delivery of ablation energy continues. If the MRSI decreases within the specified time at the specified rate, formation of a steam pocket is inferred and delivery of ablative energy is decreased or discontinued.