According to standard school models, the specific resistance (or conductivity) depends on the movability of the charges. In a metal lattice, some electrons can freely move and are only hindered by lattice impurities and lattice vibrations. These vibrations and thus the specific resistance increase with increasing temperature. When the metal melts, there is no more lattice left, so this argument can't be continued.
Does the resistance increase or decrease with the phase transition and what is the thermal behaviour in the liquid phase? And of course, why?
Possibility 1: With the phase transition, the resistance increases because the atomic rests move and thus disturb the electron flow even more.
Possibility 2: With the phase transition, the resistance jumps to nearly $\infty$, because the lattice collapses and the electrons get bound to the atoms.
Possibility 3: With the phase transition, the resistance decreases, because the atomic rests get movable as well.
In each case, I'd assume the resistance to decrease with increasing temperature in the liquid phase, because movement increases.