  In this opinion piece, we discuss recent advances in experimental methods for
characterizing phase change heat transfer. We begin with a survey of techniques
for high-resolution measurements of temperature and heat flux at the solid
surface and in the working fluid. Next, we focus on diagnostic tools for
boiling heat transfer and describe techniques for visualizing the temperature
and velocity fields, as well as measurements at the single bubble level.
Finally, we discuss techniques to probe the kinetics of vapor formation within
a few molecular layers of the interface. We conclude with our outlook for
future progress in experimental methods for phase change heat transfer.
