Lets take an example :-
Sodium superoxide has three different crystal structure, the marcasite structure at nearby 81 K, the pyrite structure between 196 K and 223 K and calcium carbide structure at room temperature.
There are many more compounds which have different structure at different temperature. If temperature is increased, bonds breaks, atoms scatters and decomposes into a different product (compound or element) . But this does not happen. Rather bond breaks, atoms rearranges to form a different structure of same compound. Why does this happen?