What happens when Borax is heated strongly ?

Explanation

Borax on heating first loses water molecules and forms sodium tetraborate. This on further heating forms a mixture of sodium metaborate and boric an hydride. This mixture is solidifies into glass like substance.
`Na_2 B_4 O_7 . 10 H_2 O overset(Delta)to underset("tetraborate")underset("Sodium")(Na_2 B_4 O_7) overset(Delta)to underset("glass like substance")ubrace(2NaBO_2 + B_2 O_3)`