Can blood that has had an anticoagulant added to it be boiled without coagulating?
Coagulation, or clotting, is a proteolytic cascade that generates an insoluble fibrin based protein net, or mesh.

Anticoagulants are things like EDTA (?) that chelate divalent cations required for the clotting cascade.

Boiling blood will denature most, if not all, of the soluble serum proteins, forming an insoluble precipitate.  This is structurally different from a blood clot.

Think about what happens to the white part of a chicken egg when you boil (or heat) it.  That is protein denaturation.