See: http://repairfaq.cis.upenn.edu/Misc/cflhole1.jpg

This is a ~1 mm hole in the glass near one of the filaments.
Something got hot enough for the glass to melt, and after
that, as they say, the rest was history.

I've seen this on 3 CFLs in 3 different lamps/fixtures. There are no known
problems that could account for such nasty behavior. They were all high
mileage, so perhaps the filament at that end of the lamp opened resulting
in the discharge going to one post, near the glass, or something.

The CFLs were all from GE but I don't know if they are of the same
ballast/lamp design.

Comments welcome.

--
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