Bring stock, water, chicken thighs, garlic, ginger, anchovies, and salt to a boil in a large saucepan. Reduce heat, and simmer until chicken is cooked through, about 15 minutes. Remove from heat.

Transfer chicken to a plate, reserving broth. Let chicken stand until cool enough to handle. Remove meat from bone, and shred into bite-size pieces.

Add chicken, kimchi, and reserved kimchi liquid to cooking broth in pan, and place pan over low heat. Gently add spoonfuls of tofu to pan, being careful not to break it. Gently shake pan to submerge tofu. Bring to a very gentle simmer, and cook until tofu is heated through, 3 to 5 minutes. Add scallions.

Divide soup among bowls, serve, and enjoy!