[UnbiasedLizard3]

So in our highschool lab we were told to make as many possible reactions happen with a bunch of given solutions and some metals. Me and my partner placed Al in some CuCl2 which, after some time, the Cu and the Al started to displace and on the outside of the Al nugget we got Cu. We then cut off this Cu to see if we could react it with anything else (kinda ignoring what the potential reaction chart said). He placed the Cu nugget in some Na2CO3, nothing happened, then he put it over some heat and the whole thing turned real cloudy, then dark brown, kinda like a really syrupy coke color, and there was still some chunks of the Cu nugget at the bottom. So I know that Na is much more reactive than Cu, so nothing should have happened, but why did what I describe above occur? Was it just the melting of the Cu into solution or is there actually some sort of reaction?

[Borek]

Sounds to me like thermal decomposition of some organic compound, are you sure Na₂CO₃ was not contaminated with something? Some sugar?