What is the short description of the crime committed the most by criminals in the least populated community?
short description refers to title; committed the most refers to max(fbi_code_no); the least populated community refers to min(population)
SELECT T3.title FROM Community_Area AS T1 INNER JOIN Crime AS T2 ON T1.community_area_no = T2.community_area_no INNER JOIN FBI_Code AS T3 ON T2.fbi_code_no = T3.fbi_code_no GROUP BY T3.title ORDER BY T1.population ASC, T3.fbi_code_no DESC LIMIT 1