Yup. The fluid packaging industry spent generations figuring out the most efficient volumetric shapes to make tanks, cans, bottles etc.—and then along came enriched uranyl nitrate solution, with its interesting habit of spontaneously becoming a reactor when put in a large enough container in any of those shapes. Atomic Accidents has a whole section that's just "people accidentally creating criticalities by mishandling fissionable liquids".

The most striking one involved a guy in a fuel reprocessing plant dumping highly-enriched uranium solution he thought was low-grade liquid waste into a giant stand mixer to homogenize it for some further operation. That one went prompt critical twice: once when the mixer bowl was full enough, and a second time when a different worker came in after the first one had been taken to the hospital and shut the mixer off, which caused the whirlpool of stuff to fall back into the bowl shape. Fortunately for the second guy, it took the mixer long enough to spin down after he shut it off that he was almost out of the room when it went off, so he "only" got a hundred rads in the back and lived (as opposed to the first guy, who got ten thousand square in the face and had all of 49 hours left in which to regret his life choices).

There was also the time during the Manhattan Project when Richard Feynman visited Oak Ridge, and discovered that though the workers there were putting the enriched solution in the long, skinny bottles as instructed, no one had told them why the bottles were long and skinny, so once said bottles were full, the workers were just stacking them up like firewood. They didn't manage to pile up enough of them to inadvertently build a reactor before Feynman noticed, but you can imagine the look on his face when he saw it.

--G.
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Benjamin D. Hutchins, Co-Founder, Editor-in-Chief, & Forum Mod
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