A refrigerator making loud noises usually tells you which component is failing by the type of sound.
Grinding or chattering from the freezer area: the evaporator-fan motor. Bearings wear out, the motor starts dragging, and the fan blade sometimes contacts ice buildup. This is a $200 to $400 repair and a very common one — and ignoring it leads to complete fan failure and loss of cooling in the fresh-food section.
Repeated clicking from the back of the unit: the compressor start relay. The relay tries to start the compressor, fails, resets, and tries again. If the compressor is otherwise healthy, a $25 relay replacement fixes it. If the compressor is seized, replacement of a 10-plus-year-old refrigerator usually beats a $600-plus compressor swap.
Humming or vibration: often a condenser-fan motor bearing or a fan blade that's contacting something (bent, or something in the coil area). Fan replacement runs $150 to $300.
A loud buzzing or a rattling can also come from the water-inlet valve on refrigerators with ice makers, or from the defrost timer on older mechanical units.
Low-level popping or cracking is normal — that's the expansion and contraction of plastic liners and shelves as temperatures change. Ignore it.