(string) connection unexpectedly closed (timed out?)

Query: SELECT SUBSTRING_INDEX(GROUP_CONCAT(keyword), ',', 8) AS related_terms FROM search_popular WHERE (keyword LIKE 'american pussy%' OR keyword LIKE 'american%' OR keyword LIKE 'pussy%') AND keyword != 'american pussy' ORDER BY hits DESC LIMIT 8
Error Message: MySQL server has gone away
Error Number: 2006