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I used T37-2 toroids, which was a bad idea as they get rather hot!
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If they get beyond about 100degC then you could enter a scary place where the coil Q will start to fall markedly. This is due to increased copper and core losses (at higher temperature) and it is possible to hit a runaway condition where the Q falls (so the losses increase) so it gets hotter and so the Q falls some more etc etc until the wire and the toroid can end up looking like it has been smoked in barbecue coals. Usually this is a fairly slow process requiring a full cw test signal into an antenna load with a poor match. It might take a few minutes to get it to the runaway condition but the coil can end up being so lossy (when hot) it resembles a low resistance dummy load. When this happens, a 50-100W transmitter will be able to properly fry a small toroid into a charred mess
This effect is more common in steep elliptic filters when the operator transmits very close to the filter cutoff and I've seen it the most in highpass filters where the inductor is fitted as a shunt component.