Wikipedia references https://en.wikipedia.org/wiki/Copper(II)_sulfate with:
Copper(II) sulfate pentahydrate decomposes before melting. It loses two water molecules upon heating at 63 °C (145 °F), followed by two more at 109 °C (228 °F) and the final water molecule at 200 °C (392 °F).
A quote from the question:
Furthermore, is there such case with a salt solution where hydrated salt version would not occur as the residue after evaporation, or vice versa with the anhydrous version?
I had a related question about Aluminum Chloride https://en.wikipedia.org/wiki/Aluminium_chloride:
Reactions with water
Anhydrous aluminium chloride is hygroscopic, having a very pronounced affinity for water. It fumes in moist air and hisses when mixed with liquid water as the Cl− ligands are displaced with H2O molecules to form the hexahydrate [Al(H2O)6]Cl3. The anhydrous phase cannot be regained on heating the hexahydrate. Instead HCl is lost leaving aluminium hydroxide or alumina (aluminium oxide):
$$\ce{[Al(H2O)6]Cl3 → Al(OH)3 + 3 HCl + 3 H2O}$$
The point being that the Bunsen burner may not be hot enough (or there alternatively may be too much humidity in the room) to completely drive out the water at "200 °C (392 °F)" for Copper(II) sulfate pentahydrate. After all, the water solvent boils nearly at 100 °C and after that, additional heating results in popping of the salt from the beaker.
Has a different oven than the Bunsen Burner been possible to use to get the Copper(II) sulfate pentahydrate decomposition temperature after full evaporation of the solvent, and slow heating to the required temperature (with some additional margin) to prevent popping of the Copper(II) sulfate pentahydrate at a lower temperature from the Bunsen Burner?