I might disagree with the first post. The heat would char the hulk’s skin, turning it into an even more menacing black juggernaut nightmare. Its skin would make toasty crunching sounds as it would leap and thump its way at you, now pissed as hell about the pesky nuke. It would still have plenty of muscle to keep going. Of course we might argue about the chemical composition, the toughness or the heat resistance of a hulk’s skin, or what they should be.
But I do agree that explosives are a bit underwhelming. I don’t find them particularly damaging or useful. Something like a C-4 charge should shred everything in the 2-tile radius (5x5 tiles), and the blastwave should send other nearby zeds outwards, colliding with objects and other zeds. Or not.
It’s not an unreasonable expectation that a hulk should be vaporized when hit by a mininuke, but if/when that fails to happen, you have to conjure up a pseudo-scientific explanation for it from the depths of your imagination in order to cope with the slight disappointment. In fact, I think it’d be awesome if everything AROUND the hulk would be vaporized by the mininuke, but the hulk would just turn into a pitch black variant with red glowing eyes, possibly via the mutation mechanics, unique only to a hulk.
Alternatively, we can speculate the heat resistance/capacity of a hulk’s internal organs, assuming it has any, or assuming they serve any vital functions. The nuke would at least cook up most things it would hit. But again, we don’t know the temperature or the amount of heat emitted by the nuke (over time), nor the heat conductivity of the hulk’s skin, fat, or muscle tissue. Nor do we know the energy of the nuke’s blastwave. It’s all wonderfully debatable!