I once got a windfall of electrolytic filter capacitors
from a place where I worked.  They were around 1,000uF at 35
volts and they were all part of a recall.  The complaint was that
they had a habit of exploding.  My boss said that they were
being operated too close to their rated voltage so I figured I'd
take the chance and just use them in supplies which were going to
produce less voltage than they originally got.

        The caps were encased in hard plastic, about thumb-sized,
and had two leads coming out one end.

        I got my windfall of about 20 or so of these in the
Summer of 1971 and used several without incident.  One day, I
switched on the power to a new supply I had built with one of
these caps and I noticed the voltage was a bit low.  Before I
could react to that, the end without the wires blew off with a
bang like a firecracker.  There was the usual smell and the
finding of bits of plastic for weeks if not months after the
bang, but I generally had no trouble with most of the caps.  I
have some of them still in use in various projects, but they are
starting to fail now by opening.  I think the ones that exploded
were defective to begin with and had an internal short.  They
would end up looking pretty much like fired shotgun shells.

Martin McCormick