Methods and apparatuses for analyzing a downhole fluid are disclosed. An example method may involve the steps of admitting the downhole fluid in a test volume, controllably inducing a pressure change in the test volume based on at least one prescribed rate, measuring pressures in the test volume at a plurality of times, using the pressures measured at the plurality of times to determine a time at which an actual rate of the pressure change in the test volume deviates from the at least one prescribed rate, and detecting an occurrence of phase transition of the downhole fluid based on the determined time.