Why did roasting of copper(II) sulfate pentahydrate hurt my nose?
Roasting of copper(II) sulfate at elevated temperatures generates sulfur trioxide, which would hurt your nose.  

$$\begin{align}
\ce{$\underset{\text{(blue)}}{\ce{CuSO4.5H2O}}$ &amp;-&gt;[\hphantom{\gt\ 200\ \mathrm{^\circ C}}][100\ \mathrm{^\circ C}] CuSO4.H2O + 4H2O}\\[6pt]
\ce{CuSO4.H2O &amp;-&gt;[\hphantom{\gt\ 200\ \mathrm{^\circ C}}][\gt\ 200\ \mathrm{^\circ C}] $\underset{\text{(white)}}{\ce{CuSO4}}$ + H2O}\\[6pt]
\ce{CuSO4 &amp;-&gt;[\hphantom{\gt\ 200\ \mathrm{^\circ C}}][] CuO + SO3}
\end{align}$$