heat up
From Longman Dictionary of Contemporary Englishheat up phrasal verb1 HOTto become warm or hot, or to make something become warm or hot The stove takes a while to heat up.heat something ↔ up I heated up the remains of last night’s supper.2 DIFFICULTif a situation heats up, it becomes dangerous or full of problems → heat→ See Verb tableExamples from the Corpusheat up• The stones heated up in the sun.• As the gas heats up, it expands.• While the oven is heating up, prepare the sauce.