Bring broth and water to a boil over high heat. Reduce heat to medium-low and add the chicken thighs, onion, thyme, bay leaf, and salt. Cook until the chicken is cooked through, about 20 to 30 minutes. Cover with lid ajar to allow some steam to escape. Remove the chicken from the broth and allow it to cool for 5 minutes. Meanwhile, add the carrots to the soup.