Shrimp Boil with Clams and Lemon

Name: Shrimp Boil with Clams and Lemon
Ingredients: Water; 2 lemons, halved, plus more for serving; 3 bay leaves; 2 teaspoons salt; 1/4 cup crab boil seasoning (recommended: Old Bay); 1/2 bunch thyme, tied together; 1 medium onion, quartered; 2 serrano chiles, split in 1/2 lengthwise; 1 head garlic, halved; 1 pound 5 ounces red new potatoes, medium to large, cut in 1/2; 3 ears sweet corn, halved; 3 pieces smoked sausage, such as andouille or kielbasa, cut into 1-inch pieces (about 1 pound 5 ounces); 12 littleneck clams, scrubbed (about 1 pound 4 ounces); 2 pounds jumbo shrimp with heads and tails; Kosher salt