The results of an experimental study on critical heat fluxes (CHF) during the nucleate boiling of the HFE-7100 dielectric liquid in horizontal layers of different heights at atmospheric pressure are presented. The existence of a critical layer height has been established. In layers above the critical layer height, a hydrodynamic boiling crisis occurs; in thinner layers, a surface drying crisis occurs. At a layer height equal to the critical value, a dry spot first appears, followed by transition boiling, which gradually spreads to the entire heating surface. In these experiments, the critical layer height was equal to 6 mm. In a layer of liquid with a critical layer height of 6 mm, a two-dimensional Taylor instability was observed in the transition boiling mode when the ratio of the diameter of the “vapor jets” to the distance between them, as well as the void fractions in the layer (~π/16), corresponded to the main provisions of the Zuber theory. The calculation of CHF using the relations of Zuber’s theory, when approaching the crisis from the transition boiling side and taking into account the real geometric dimensions, aligns well with the experimental results.