Yes, thanks, your latest quote is much better. The first one was apparently just a case of sloppy writing. It implied that Calcium and Magnesium carbonates are somehow decomposed by boiling water temps. It is the Bicarbonates that are unstable, and decompose to carbonates, which may precipitate if the concentration is high enough. I'm not sure how much it actually softens the water--it certainly depends on initial mineral concentrations, but it surely wont make soft water out of hard water.
Ed