  We describe a new method for robustly testing theoretical predictions of red
giant evolution near the tip of the giant branch. When theoretical cumulative
luminosity functions are shifted to align the tip in I-band and normalized at a
luminosity level slightly brighter than the red giant bump, virtually all
dependence on age and composition (heavy elements and helium abundance) is
eliminated. While significant comparisons with observations require large
samples of giant stars, such samples are available for some of the most massive
Milky Way globular clusters. We present comparisons with the clusters NGC 2808
and M5, and find that NGC 2808 has a deficiency of bright giants (with a
probability of less than about 3% that a more extreme distribution of giant
stars would have happened by chance). We discuss the possibilities that
underestimated neutrino losses or strong mass loss could be responsible for the
deficit of giants. While we cannot rule out the neutrino hypothesis, it cannot
explain the apparent agreement between the M5 observations and models. On the
other hand, strong mass loss provides a potential link between the giant star
observations and NGC 2808's unusually blue horizontal branch. If the mass loss
hypothesis is true, there is likely a significant population of He white dwarfs
that could be uncovered with slightly deeper UV observations of the cluster.
