Write SQL query to solve given problem: Describe the students' full names and GPAs under the supervision of the most popular professor.. Keep the solution inside sql tag ```sql [SQL-Query] ```
SELECT T3.f_name, T3.l_name, T3.gpa FROM prof AS T1 INNER JOIN RA AS T2 ON T1.prof_id = T2.prof_id INNER JOIN student AS T3 ON T2.student_id = T3.student_id ORDER BY T1.popularity DESC LIMIT 1