1. A method performed by a data processing apparatus, the method comprising: receiving, during a current search session for a user device, a set of queries; identifying, as similar search sessions, multiple previous user search sessions based on a query path that the current search session shares with the similar search sessions, each similar search session including at least a threshold percentage of search queries that match search queries in the set of queries of the current search session; identifying, as concluding search queries, each search query that concluded at least one of the similar search sessions by being a final search query received during the at least one similar search session; determining, for each concluding search query, a popularity of the concluding search query based on a total number of the similar search sessions that the concluding search query concluded; selecting, from the concluding search queries and as a most popular query modification, a given concluding search query in response to (i) the popularity of the given search query being greater than the popularity of each other concluding search query and (ii) the popularity of the given concluding search query being greater than a suggestion threshold; and providing, to the user device, query suggestion data that initiates presentation of the given search query as the most popular query modification associated with the current search session at the user device.
1. A method performed by a data processing apparatus, the method comprising: receiving, during a current search session for a user device, a set of queries; identifying, as similar search sessions, multiple previous user search sessions based on a query path that the current search session shares with the similar search sessions, each similar search session including at least a threshold percentage of search queries that match search queries in the set of queries of the current search session; identifying, as concluding search queries, each search query that concluded at least one of the similar search sessions by being a final search query received during the at least one similar search session; determining, for each concluding search query, a popularity of the concluding search query based on a total number of the similar search sessions that the concluding search query concluded; selecting, from the concluding search queries and as a most popular query modification, a given concluding search query in response to (i) the popularity of the given search query being greater than the popularity of each other concluding search query and (ii) the popularity of the given concluding search query being greater than a suggestion threshold; and providing, to the user device, query suggestion data that initiates presentation of the given search query as the most popular query modification associated with the current search session at the user device. 3. The method of claim 1 , wherein the similar search sessions are identified from a set of previous search sessions for multiple different users.