When it’s boiled to dryness, crown ether can produce peroxides that are unstable enough to explode on their own with shock or additional heat - no oxygen needed.
It’s a not-uncommon mistake to make in a synthetic lab.
My understanding is that evaporating solvent away doesn't form peroxides. Rather, as an ether ages, it can peroxidize. Removing the solvent concentrates the peroxides is all. Sure, it's a little tricky, but they're reporting results of chemistry research, which doesn't mean immediate real world application.
