Worth noting that if you grow salt crystals that they need to be kept in very dry conditions. sodium chloride is hygroscopic and absorbs water vapour from the atmosphere so the crystals will ‘bloom’ unless they are protected. A sealed container with a few silica gel packs will keep them safe.
This takes me back to my many unsuccessful childhood attempts to grow large crystals of potassium alum and copper sulfate using the same method. The local chemist did very well out of all my purchases, but probably thought I had some weird medical condition.
