The phrase "fall to bits" refers to something that breaks down or falls apart completely. There are several synonyms for this phrase, including "break down," "disintegrate," "crumble," "dismantle," "collapse," and "decompose." Each of these words implies a different type of deterioration. "Break down" suggests a mechanical failure, while "disintegrate" implies a gradual loss of cohesion or structure. "Crumble" and "dismantle" both suggest a deliberate or accidental destruction. "Collapse" implies a sudden and catastrophic failure, while "decompose" suggests a gradual breakdown of organic matter. All of these words can be used interchangeably with "fall to bits" to describe something that is no longer functional or intact.