What was the maximum weight of the shipment carried to Boston? Name the customer of that shipment.
"Boston" is the city_name; maximum weight refers to Max(weight); customer refers to cust_name
SELECT T1.weight, T2.cust_name FROM shipment AS T1 INNER JOIN customer AS T2 ON T1.cust_id = T2.cust_id INNER JOIN city AS T3 ON T3.city_id = T1.city_id WHERE T3.city_name = 'Boston' ORDER BY T1.weight DESC LIMIT 1