Induction heating

If paramagnetic substance gets magnetized then it will warm little bit. Single magnetization doesn't warm so much that skin could sense difference as iron put against magnet can demonstrate but induction heaters use alternating currents with frequencies usually between 10-400 kHz so material can get magnetized in different directions over 800 000 times per second (in case of 400 kHz AC). Materials that magnetize easier warm up faster this way.
Such heater are built somewhat like inductors where wire is coiled around some metal which absorbs energy from wires as magnetic energy but "wires" in these heaters are very thick as they need lot of current for quick magnetization plus these copper wires are often fluid cooled. Magnetic energy that wires create depends equally on amperes and number of wire turns around material (ampere-turns).

Example of some attributes of this heater. While it uses high current it is somewhat safe to touch metal while it is being heated without getting electrocuted. He holds bare fingers against it for several seconds before he starts to move them away from glowing part. He later touched the wires which didn't get very hot. Only the part between wires seems to heat up and this 15 kW heater got that metal glowing in about 10 seconds.