From Anna's link: Alkali metals can explode if they are exposed to water.

The Alkali Metals are:
Lithium
Sodium
Potassium
Rubidium
Cesium
Francium
I seem to recall warnings about cesium in chemistry class. I find it a little startling that the first 3 on this list (that I know of) are ingested by humans; presumably they are "fixed" in some way so as to prevent them from exploding when you put them in your mouth and add water so you can swallow them!

Well, shoot--another "bright idea" of mine shot down: the word cesium made me think of cerise, but: [From Latin caesius, bluish gray (from its blue spectral lines).] (Atomica)

As to the alkali/lye connection, I think that surely there must be one, never mind Bartleby's Old English, Germanic, Old Norse, Latin, and Greek citations for lye. Look, these roots all mean soap, lathering, washing, etc. AND, Arabic al-qily, the ashes : lye soap was/is made from ashes! That's just too close to be coincidence, methinks.

I noticed that Bartleby listed our old friend:lutefisk

SYLLABICATION: lu·te·fisk
PRONUNCIATION: lt-fsk
VARIANT FORMS: also lut·fisk ( ltfsk)
NOUN: A traditional Scandinavian dish prepared by soaking air-dried cod in a lye solution for several weeks before skinning, boning, and boiling it, a process that gives the dish its characteristic gelatinous consistency.
ETYMOLOGY: Norwegian : lut, lye (from Swedish, from Old Norse laudhr, soap, foam; see leu()- in Appendix I) + fisk, fish (from Old Norse fiskr).
Must say the final description makes my gorge rise...