Borax ($N{a}_2{B}_4{O}_7\cdot 10H_{2}O$) undergoes a two-step transformation upon heating:

1. Consistently heating causes it to lose water of crystallization and swell into a white porous mass of anhydrous $N{a}_2{B}_4{O}_7$.
2. On strong heating, it melts to a transparent liquid which solidifies into a glassy 'Borax Bead'.

• Chemistry: The bead is a mixture of Sodium Metaborate ($NaB{O}_2$) and Boric Anhydride ($B_2{O}_3$).
• Reaction: $N{a}_2{B}_4{O}_7\to 2NaB{O}_2+B_2{O}_3$.