After the piece cools a specific tension is created in the piece due to different coefficients of expansion of metal and enamel. Plique-a-jour pieces, due to the open back, are more fragile than other kinds of enamels.
Cut an old water heater in half. It was so cute after the flowers started filling out. I didn't add legs but your handy husband/boyfriend could weld some on. Just sitting it on a bed of rocks was perfect.