Determining which hydrate of calcium chloride I have?
The mass of your sample decreased by 22%.  

If you originally had $\ce{CaCl2.4H2O}$ and quantitatively dehydrated that to $\ce{CaCl2.H2O}$, then you should have seen a decrease in mass of 27%.  

If you originally had $\ce{CaCl2.4H2O}$ and quantitatively dehydrated that to $\ce{CaCl2.2H2O}$, then you should have seen a decrease in mass of 18%.  

Although it's tempting to say that you just have some mix of mono-and-dihydrates, I think that we just can't ignore the stability of your mass measurements and the temperature of your sample, which due to the radiative heating from the toaster heating coils was probably even greater than $\mathrm{350^oF}$. The most reasonable option remaining is that you originally had primarily $\ce{CaCl2.4H2O}$, but also some $\ce{CaCl2.6H2O}$ mixed in, and now you have just the monohydrate remaining.