Loud crackling sound outside coolcat while running

My coolcat a/c was running in humid conditions yesterday.  Condensate pooled up in the plastic tray under the radiator, visible through the outside grille. To water drawing to the ground, though. There was a loud crackling sound coming from beneath the radiator, as it the radiator coils were very hot and contacting the water and splattering.  Is this normal?  Outside temp near 90, inside temp about 82.  Humidity outside was about 65%.