Gerald Ross wrote in :

Got a wind fall of Eucalyptus couple of weeks ago, and promptly cut it
into bowl blanks and end sealed it. I turned a couple of roughs and end
sealed them inside and out. Got back from vacation and the bowls were
trying to turn into pretzels, with rim cracks of 1 inch depth.
Re rounded one and threw it into LDD overnight. Yesterday I tried to
finish it, but it started moving while sanding. Turned into a potato
chip instead of a pretzel.
This is real energetic wood. Have a picture posted on ABPW along with a
picture of a piece of bowl blank that I sawed off and end sealed on both
ends 2 weeks ago.

There are many types of eucalyptus, or gum, trees. Some are well-suited
for lumber, others not. It's my understanding that gum trees were imported
into California for lumber, but oops!, they were of the not-good-for-lumber
variety, and also grow like weeds, hence their presence all over the dang
place. That variety grows so fast that it is very weak. My mom was almost
killed by a huge branch which fell just behind her car.

--
John Snow
"If I knew what I was doing, I wouldn't be here"